In P.E.R.C. No. 2012-47, the Commission restrained arbitration over the County’s refusal to place a building service worker who became qualified as an LPN into an open LPN position. The County is a Civil Service jurisdiction and the position is subject to a 90-day working test period. The Commission had long held that senior qualified employees have a mandatorily negotiable interest in seeking a trial period to demonstrate that the employer, in its discretion, should permanently promote them. The Commission distinguished only two trial period cases, one on the ground that the trial period applied to a temporary promotion and the other on the ground that the employer did not contest the qualifications of the grievant. However, the Commission had also applied its trial period case law to permanent promotions, not just temporary ones, and the County in this case did not claim that the grievant was not qualified for the LPN position. The County simply asserted that another candidate was more qualified. Thus, the Commission deviated from prior case law without either distinguishing that case law or overruling it.